The present invention relates generally to medical devices and methods, and more specifically to transluminal devices, systems and methods which are useable to enlarge interstitial tracts (e.g., man made puncture tracts or small passageways) which extend between two (2) anatomical conduits (e.g., blood vessels) or otherwise through tissue(s) within a mammalian body.
Applicant has devised several new medical procedures wherein passageway-forming catheters are advanced into anatomical conduits (e.g., blood vessels) and are used to create one or more interstitial passageways which extend outwardly, from the conduit in which the catheter is positioned, to another conduit or anatomical structure. Some of these procedures may be used to form flow-through passageways between the anatomical conduit (e.g., blood vessel) in which the passageway-forming catheter is positioned, and another anatomical conduit (e.g., another blood vessel) or a different location on the same anatomical conduit (e.g., a downstream site on the same blood vessel). Alternatively, these procedures may be used to form access passageways between the anatomical conduit (e.g., blood vessel, urethra, fallopian tube, etc.) and another anatomical structure (e.g., a tumor, organ, muscle, nerve, etc.).
In at least some of applicant""s procedures, the interstitial passageway(s) are initially formed by advancing a tissue-penetrating element (e.g., a small diameter needle or a flow of tissue-penetrating energy) from the passageway-forming catheter, through the wall of the anatomical conduit in which the catheter is positioned, and into the target location. In some cases, the interstitial passageway which is formed by the initial passage of the tissue-penetration element from the passageway-forming catheter is of relatively small diameter-and must subsequently be enlarged (e.g., debulked, dilated, expanded, stretched) to accommodate the desired flow of biological fluid (e.g., blood) or passage of other substances/devices therethrough.
In particular, as described in applicant""s earlier-filed U.S. patent applications Ser. Nos. 08/730,327 and 08/730,496, such enlargement of the initially formed interstitial passageway (e.g., penetration tract) may be particularly important when the procedure is being performed to by-pass an obstruction within a coronary artery. For example, in some of applicant""s procedures, a primary interstitial passageway is formed between an obstructed coronary artery and an adjacent coronary vein, such that blood will flow from the obstructed artery into the adjacent coronary vein. In such applications, the arterial blood which enters the adjacent coronary vein through the primary interstitial passageway is allowed to retroperfuse the ischemic myocardium by retrograde flow through the coronary vein. In other of applicant""s procedures, one or more secondary interstitial passageways are formed between the coronary vein into which the arterial blood has flowed and the obstructed artery (or some other coronary artery) to allow arterial blood which has entered the coronary vein to reenter the obstructed artery (or some other coronary artery), after having bypassed the arterial obstruction. Thus, in either of these interventional procedures, it is important that the primary and/or secondary interstitial passageway(s) remain patent and sufficiently large in diameter to support the continued flow of arterial blood to the myocardium. However, the task of enlarging the small diameter interstitial passageway(s) (e.g., puncture tracts) formed by the initial passage of the tissue-penetrating element presents numerous technical challenges.
The prior art has included a number of catheter-based devices which may be used to enlarge or remove obstructive matter from the lumen of a blood vessel or other anatomical conduit (e.g., a blood vessel). These devices include; atherectomy catheters, embolectomy catheters, balloon angioplasty catheters, laser ablation catheters, etc. However, these prior art lumen-enlarging/lumen-clearing devices have typically not been intended for use in small diameter puncture tracts which diverge at an angle from the conduit lumen in which the catheter is located, as is typically the case in applicant""s above-summarized interventional procedures.
Accordingly, there exists a need for the design and development of a new device, system and method for enlarging interstitial penetration tracts (e.g., man-made punctures or small passageways) which extend between adjacent anatomical conduits (e.g., blood vessels) within a mammalian body.
The present invention provides devices which are useable in combination with each other (i.e., as a system) to enlarge an interstitial tract (e.g., a small diameter penetration tract through tissue) which extends from a blood vessel or other anatomical conduit of the body. The tract enlarging systems of the present invention generally fall into three (3) major classificationsxe2x80x941) debulking-type systems, 2) dilating-type systems, 3) slicing-type systems and 4) two-catheter systems.
In accordance with the invention, one debulking-type tract enlargement system (referred to herein as an xe2x80x9cadvanceablexe2x80x9d debulker) generally comprises: a) an elongate, pliable, tubular sheath sized for insertion into the lumen of an anatomical conduit from which the interstitial tract extends, said sheath having a lumen which extends longitudinally therethrough; b) a counter-traction member which is advanceable, i.) through the lumen of the tubular sheath and ii.) at least partially through the interstitial tract, such that the countertraction member engages or becomes positioned in relation to tissue which lies adjacent the interstitial tract to thereafter exert proximally-directed force upon such tissue; and, c) a debulker""(e.g., a tissue removing apparatus or flow of energy) which is advanceable out of the lumen of the sheath in a distal direction (i.e., substantially opposite the proximally-directed force being exerted by the counter-traction member) to remove tissue from the area adjacent the tract.
Further in accordance with the invention, there is provided another debulking-type tract enlargement system (referred to herein as a xe2x80x9cretractablexe2x80x9d debulker) generally comprises: a) an elongate, pliable, tubular sheath sized for insertion into the lumen of an anatomical conduit from which the interstitial tract extends, said sheath having a lumen which extends longitudinally therethrough, and b) a pull-back debulker (e.g., a tissue-removing apparatus or flow of energy) which is i.) initially advanceable out of the lumen of the sheath in a distal direction so as to pass through the penetration tract which is to be enlarged, and ii.) thereafter retractable in the proximal direction so as to remove, tissue which lies adjacent the interstitial tract, thereby enlarging the interstitial tract.
Still further in accordance with the invention, there is provided a dilating-type tract enlargement system (referred to herein as a xe2x80x9cdilatingxe2x80x9d system) which generally comprises: a) an elongate, pliable, tubular sheath sized for insertion into the lumen of an anatomical conduit from which the interstitial tract extends, said sheath having a lumen which extends longitudinally therethrough, and b) a dilator (e.g., an elongate member) having at least one tissue-dilating member (e.g., a tapered, frusto-conical member, balloon or radial deployable member(s)) formed thereon, such dilator being advanceable into the penetration tract which is to be enlarged, and is subsequently useable to dilate such penetration tract, thereby resulting in the desired enlargement thereof. A positioning surface may be formed on the dilator to abut against tissue which lies adjacent the passageway in a manner which will enable the operator to determine that the dilator has been advanced to its desired position and is properly located to allow the dilate the interstitial tract as desired.
Still further in accordance with the invention, there is provided a slicing-type tract enlargement system (referred to herein as a xe2x80x9ctissue-slicingxe2x80x9d system) which generally comprises a) an elongate shaft which is advanceable through the interstitial tract, and b) at least one tissue slicing member which extends or is extendable from the shaft to incise or cut tissue which lies adjacent the interstitial tract as the shaft is advanced and/or retracted through the tract. In some embodiments, the tissue slicing member(s) may be initially disposed in a radially compact configuration which is flush with, or only slightly protrusive beyond, the outer surface of the shaft, thereby allowing the shaft to be advanced through the interstitial tract without cutting or disrupting the surrounding tissue. Thereafter, the tissue slicing member(s) is/are shifted to a radially expanded configuration wherein such tissue-slicing member(s) extend or protrude laterally from the shaft so as to slice, incise or cut at least some of the tissue which surrounds the tract. The tissue-slicing member(s) need not be concentric about the shaft, but rather may be of substantially flat configuration so as to create a defined incision or cut in the tissue. Moreover, the tissue-slicing member(s) may be configured so as not to completely sever and remove tissue in the manner of the above-summarized debulking-type embodiment, but rather may simply form a lit or incision adjacent the tract such that the surrounding tissue will continuously or intermittently separate to allow flow of fluid (e.g., blood) therethrough.
Still further in accordance with the invention, there is provided a two-catheter type tract enlarging system (referred to herein as a xe2x80x9ctwo-catheterxe2x80x9d system) which is specifically useable to enlarge an interstitial tract or passageway which has been formed between two adjacent anatomical conduits (e.g., blood vessels). Such two-catheter system generally comprises a) a first catheter having a tract-enlarging apparatus (e.g., a debulker, dialtor or tissue-slicing member of the above-described nature) which is advanceable from an opening at or near the distal end of that catheter, and b) a second catheter which has an anvil member (e.g., an abuttable surface or receiving cavity) which is sized and configured to correspond with the leading end of the tract-enlarging apparatus of the first catheter. The first catheter is positioned in one of the anatomical conduits, and the second catheter is positioned in the other anatomical conduit, with its anvil member located next to the interstitial tract or passageway which is to be enlarged. Thereafter, the tract enlarging, apparatus is advanced through the tract or passageway until it registers with (e.g., abuts against or is received with) the anvil member of the second catheter. As the tract enlarging apparatus is being advanced, the anvil member serves to provide counterforce against the tissue adjacent the initially formed tract or passageway so as to prevent unwanted protrusion or xe2x80x9ctentingxe2x80x9d of the tissue into the second anatomical conduit, and to ensure efficient cutting of the tissue in cases where a debulking or tissue slicing type tract enlarging apparatus is used.
Still further in accordance with the invention, either the debulking-type, dilating type, tissue-slicing type or two catheter type tract enlargement systems of the present invention may incorporate a guidewire lumen which extends longitudinally through the i.) tract enlarging member (e.g., debulker, dilator or tissue slicing member) to permit the tract enlarging member to be advanced over a small guidewire which has previously been passed through the penetration tract which is to be enlarged. Thus, the provision of such guidewire lumen may permit the system to be used to dilate penetration tracts which are of extremely small diameter, or which have become substantially closed off due to constriction of the surrounding tissue, provided that a guidewire was previously inserted through such penetration tract.
Still further in accordance with the invention, energy such as radio-frequency energy or electrical resistance heat may be applied to the tract enlarging member (e.g., debulker, dilator, or tissue slicing member) to enhance the tract-enlarging efficiency thereof.
Still further objects and advantages of the present invention will become apparent to those of skill in the relevant art, upon reading and understanding of the following detailed description of the invention and the accompanying drawings.